A typical hangover lasts about 18 hours after your last drink, though most people experience it as roughly 12 hours of symptoms after waking up. The range for most drinkers falls between 14 and 23 hours total, and symptoms can stretch beyond 24 hours after heavy drinking.
When Symptoms Start and Peak
Hangover symptoms don’t hit the moment you stop drinking. They begin as your blood alcohol level drops toward zero, which for most people happens while they’re asleep. In practical terms, severity scores start climbing about 8 hours after drinking and peak around 14 hours after your first drink. If you started drinking at 6 p.m. and stopped around midnight, that peak lands somewhere around 8 a.m. the next morning.
From there, symptoms gradually taper. Most people feel noticeably better by the afternoon or early evening, but lingering fatigue and brain fog can stick around longer than the headache and nausea do.
What’s Happening in Your Body
Your liver breaks alcohol down in stages. First, it converts ethanol into a toxic byproduct called acetaldehyde, then converts that into harmless acetate. The problem is that acetaldehyde is highly reactive. While it’s circulating, it damages cells by ramping up oxidative stress and disrupting your mitochondria, the energy-producing structures inside your cells. That means your cells literally produce less energy than normal, which helps explain the deep fatigue of a hangover.
Acetaldehyde isn’t the whole story, though. Research shows that some hangover effects, particularly changes to proteins involved in brain signaling, persist even when acetaldehyde is neutralized. This points to multiple overlapping mechanisms, not just one toxin making you feel terrible.
Your immune system also gets involved. During a hangover, your body produces elevated levels of certain immune signaling molecules, the same ones your body ramps up when you’re fighting an infection. That’s why a hangover can feel eerily similar to being sick: the nausea, headache, diarrhea, and fatigue are partly driven by your own immune response reacting to what alcohol did to your system.
Factors That Make a Hangover Last Longer
The single biggest factor is how much you drank. More alcohol means more acetaldehyde to process, more immune disruption, and a longer recovery window. But several other variables can stretch a hangover well past the typical 18-hour mark.
What you drank matters. Darker alcoholic beverages like bourbon, whiskey, and red wine contain higher concentrations of congeners, trace chemicals produced during fermentation. These congeners correlate with more numerous and more severe hangover symptoms. Vodka and other clear spirits have far fewer congeners, and studies comparing bourbon to vodka drinkers consistently find worse hangovers in the bourbon group, even at the same alcohol dose.
Sleep quality plays a direct role. Alcohol suppresses REM sleep and increases the time you spend awake during the night, even if you don’t remember waking up. People with lower sleep efficiency after drinking report significantly worse hangover severity, and those with the highest hangover scores also spend less total time asleep. Poor sleep doesn’t just add fatigue on top of a hangover. It appears to worsen the hangover itself.
Your age changes the equation. As you get older, your liver produces fewer of the enzymes responsible for breaking down alcohol. That means alcohol and its toxic byproducts stay in your system longer, extending both the duration and intensity of symptoms. A night of drinking that produced a manageable morning-after at 25 can easily turn into a full-day ordeal at 40.
The Two-Day Hangover
Hangovers lasting longer than 24 hours are not uncommon after particularly heavy drinking sessions. The NIAAA notes that symptoms can persist beyond 24 hours, and anecdotally, many people report feeling “off” for two full days after a binge. This is more likely when multiple factors stack up: high volume of alcohol, dark spirits with lots of congeners, poor sleep, dehydration, and an empty stomach.
Trying to cure a hangover with more alcohol the next morning, sometimes called “hair of the dog,” temporarily masks some symptoms but actually prolongs the overall recovery. You’re giving your body more ethanol to process, which delays the point at which your system fully clears the toxins.
What Actually Helps You Recover Faster
There’s no proven hangover cure, but a few things meaningfully support recovery. Rehydrating is the most straightforward: alcohol suppresses a hormone that helps your kidneys retain water, so you lose fluids faster than normal while drinking. Water, electrolyte drinks, or broth help restore what was lost.
Eating can help stabilize blood sugar, which drops during heavy drinking and contributes to shakiness and weakness. Simple, bland foods tend to be easiest to tolerate when nausea is still present.
Sleep is the other major lever. Since alcohol disrupts sleep architecture the night of drinking, napping the next day gives your brain a chance to get the restorative sleep it missed. Given that reduced sleep efficiency directly worsens hangover severity, even an extra hour or two of rest can make a real difference in how quickly you bounce back.
Beyond that, time is the only reliable remedy. Your liver processes alcohol at a fixed rate, and there’s no supplement or food that meaningfully speeds up that process. Most people can expect to feel like themselves again within 12 to 24 hours of waking up, with the worst of it concentrated in the morning and early afternoon.